Joiful Dynamo

What this package does?

Joiful-Dynamo uses Typescript Decorators to easily let developers to manage data models. This IS NOT a complete ORM, but a facilitator to make the experience of using AWS DynamoDB easier and with less code repetition. This packages was developed with the Single Table Adjacency List Design Pattern in mind.

The decorators includes:

• validate that relies on Joi for a very customizable validation experience
• aliases and aliasTo for creating property aliases without duplicating data and columns in the database.
• compositeKey for creating well designed sort keys that helps filtering and sorting data.
• hasOne and hasMany for creating data relations. Relations can be nested data (saving the data as a map inside the parent record) or totally separate records in the same dynamodb table.

See the full docs at https://chocolate-soup-inc.github.io/joiful-dynamo/.

Why

Using AWS DynamoDB is always a very challenging and verbose experience. Some packages achieved very good experiences when interacting with data, like TypeORM and Sequelize but they don't connect to DynamoDB. Some dynamodb libraries are awesome (like DynamoDB Toolbox) but misses some basic functionality like data validation and transforming. Also, if you want to use a one table design it gets even harder to find complete solutions. So, joiful-dynamo connects the experience of using Joi as a validation library to a better experience with dynamodb.

As this library was architected with single table design in mind, if you want to use a multi table design, use it at your own risk.

Installation

1. Install the package:

npm i --save @chocolatesoup/joiful-dynamodb

2. Install reflect-metadata:

npm install reflect-metadata --save

3. You may need to install node typings:

npm install @types/node --save-dev

4. TypeScript configuration Also, make sure you are using TypeScript version 3.3 or higher, and you have enabled the following settings in tsconfig.json:

"emitDecoratorMetadata": true,
"experimentalDecorators": true,

You may also need to enable es6 in the lib section of compiler options, or install es6-shim from @types.

Basic Usage

import {
  Entity,
  aliases,
  aliasTo,
  props,
  table,
  validate,
} from '@chocolatesoup/joiful-dynamo';

import * as Joi from 'joi';

@table('test-table')
class TestModel extends Entity {
  @prop({ primaryKey: true });
  @validate(Joi.string().required())
  @aliases(['primary'])
  pk: string;

  @prop()
  @validate(Joi.string().trim().required())
  name: string;

  @prop()
  @aliasTo('name')
  fullName: string;

  @prop({ createdAt: true })
  _createdAt: string;

  @prop({ updatedAt: true })
  _updatedAt: string;
}

const instance = new TestModel({
  pk: '1',
  fullName: '   test name  ',
  extraAttribute: 'extra',
});

// this should be inside an async function
await instance.create();
/*
  Data saved to DB:
  {
    pk: 'TestModel-1',
    name: 'test name',
    extraAttribute: 'extra',
    _createdAt: '2022-02-07T22:43:30.344Z',
    _updatedAt: '2022-02-07T22:43:30.344Z',
    _entityName: 'TestModel',
  }
*/


const invalidInstance = new TestModel({
  name: 'Name',
});

console.log(invalidInstance.valid) // false
invalidInstance.create() // Throws error.


const dbInstance = await TestModel.getItem({ pk: '1' });
dbInstance.name = '123'
dbInstance.update();


const scanInstances = await TestModel.scan(); // scanAll also available
console.log(scanInstances.items) // Array of test instances
await scanInstances.next() // Load next page
console.log(scanInstances.items) // Array with ALL test instances
console.log(scanInstances.lastPageItems) // Array with last page instances

const queryOpts = {
  IndexName: 'byEntity',
  KeyConditionExpression: '_entityName = :e',
  ExpressionAttributeValues: {
    ':e': 'TestModel',
  },
};
const queryInstances = await TestModel.query(queryOpts); // queryAll also available
console.log(queryInstances.items) // Array of test instances
await queryInstances.next() // Load next page
console.log(queryInstances.items) // Array with ALL test instances
console.log(queryInstances.lastPageItems) // Array with last page instances

For more examples and full docs, access https://chocolate-soup-inc.github.io/joiful-dynamo/.

Additional References

• AWS SDK DocumentClient Reference
• Best Practices for DynamoDB
• Single Table Adjacency List Design Pattern

Contributions and Feedback

This package definitely has a lot of space for new features and improvements, so please contribute! =)

Contributions, ideas and bug reports are welcome and greatly appreciated. Please add issues for suggestions and bug reports or create a pull request.